The invention relates to a method for operating a radio communication system which makes provision for the relaying of data of connections via subscriber stations which temporarily fulfill the function of routing nodes. The invention further relates to a method for routing a connection in a radio communication system of said kind, as well as to a corresponding subscriber station and a corresponding routing unit.
Communication in radio communication systems is effected by electromagnetic waves over an air interface. One type of radio communication systems are the mobile radio systems. Known mobile radio systems of the so-called “second generation” are the US IS-95 standard and GSM (Global System of Mobile Communication). At the present time mobile radio systems of the third generation are in the process of being built, for example systems conforming to the FDD (Frequency Division Duplex) variant of the UMTS (Universal Mobile Telecommunication Standard) standard. The cited mobile radio systems are generally organized on a cellular basis, which is to say that they have a plurality of base stations, each of which provides coverage of a radio cell. The subscriber stations communicate with a base station located in the vicinity, in whose radio cell they find themselves.
Also known are what are referred to as wireless ad hoc networks in which signals of a connection are forwarded exclusively or partially via a plurality of subscriber stations acting as routing nodes. An ad hoc network of said type is described in L. Weifa et al: Maximizing Battery Life Routing in Wireless Ad Hoc Networks, IEEE Proceedings of the 37th Hawaii International Conference on System Sciences, 2004. Said paper describes a routing algorithm in which the battery power of the individual subscriber stations that may be suitable as routing nodes is taken into account. In particular said algorithm takes into account information relating to batteries with different charge capacity that are used in the subscriber stations.
In S. Lakkavalli et al: Using Remaining Battery Lifetime Information and Relaying to Decrease Outage Probability of a Mobile Terminal, published on the internet before the date of filing of the present application, there is a description of a cellular mobile radio network which likewise has an ad hoc component. Mobile subscriber stations transmit information relating to the charge condition of their battery to a base station. The base station is then able to calculate the maximum possible transmission power for the corresponding subscriber station. A distinction is made between routing nodes (relays) which have unlimited battery power because, for example, they are connected to the power supply of an automobile, and routing nodes with limited battery power.
WO 03/055246 A1 discloses a mobile communication network in which mobile stations having a relay function are used. In this arrangement a mobile communication network comprises mobile terminals including a fixed station for exchanging signals with a first mobile terminal. A second mobile terminal is configured in such a way as to exchange so-called relay signals between said fixed station and said first mobile terminal.
WO 02/51038 A1 discloses a billing method wherein mobile devices are used as relay equipment.
WO 02/080405 A1 discloses a communication relay device wherein the relay function is used only when there is a connection to an external power source.
WO 2004/034642 AI discloses a method for routing a connection from a first mobile station to a second mobile station, wherein a central routing unit receives positioning information and transmits routing information to the mobile stations.